The present disclosure relates to a method for determining a probability of tipping in the case of an industrial truck, such as, for example, a fork-lift truck.
Fork-lift trucks (known as FLTs) from different manufacturers are of very similar design in terms of the chassis. A front axle drive with a front axle which is permanently mounted on the body, a rear axle steering system with a pendulum axle and virtually complete elimination of a suspension system (only the tire has elastic properties) are predominant. The steering system is usually embodied as a hydrostatic steering system, i.e. the steering wheel angle is transferred to the wheel steering angle via hydraulic connection elements. The lift mast with the load fork is mounted in from of the front axle, and the driver is seated between the axles. The drive of the fork-lift truck generates both the driving torques and the braking torques via the drive train. A service brake which acts on all four wheels is usually not provided.
Fork-lift trucks are very compact, i.e. narrow and short, in design, very maneuverable and can lift large loads to a great height. In this context, there is, under certain circumstances, a high risk of tipping over during the taking up of the load, during driving and in particular on roadways which have an incline since the loads on the fork shift the entire center of gravity of the fork-lift truck to a great extent, and, under certain circumstances, very greatly reduce the static and dynamic tipping stability of the fork-lift truck during travel, which cannot always be predicted by the driver.
Within the scope of this disclosure, subsequent terms and definitions are used:
The x axis points in the direction of travel, and the y axis points perpendicularly thereto to the right along the front axle. The z axis is perpendicular to the x-y plane and points downward. (right-handed system). The rotation about the x axis (longitudinal axis) is referred to as rolling, the rotation about the y axis (transverse axis) as pitching and the rotation about the z axis (vertical axis/yaw axis) as yawing.
DE 103 04 658 A1, to which reference is expressly made for details regarding the stability model on which a fork-lift truck is based, discloses a device for controlling the driving stability of an industrial truck and a method for actuating an industrial truck. The load, the inclination of the mast and the lifting frame, the lifting height of the load, the tipping forces acting on the mast and the accelerations acting in the longitudinal direction and transverse direction on the vehicle are detected by means of a sensor system and compared with predefined limiting values. These limiting values which are dependent on the driving state cannot be arbitrarily exceeded by the driver, with the result that the vehicle generally remains stable irrespective of the driving state (cornering, straight-ahead travel, downhill travel . . . ).
It is desirable to specify an improved method for determining a probability of tipping in order then, if appropriate, to able to react more quickly in order to prevent tipping.